1. Field of the Invention
The present invention relates to a backrest supporting assembly that provides improved supporting stability and improved seating safety.
2. Description of the Related Art
FIGS. 5 and 6 of the drawings illustrate a conventional chair including a backrest 1xe2x80x2, a seat 2xe2x80x2, a chassis 3xe2x80x2, a leg assembly 4xe2x80x2, and a substantially L-shaped connecting plate 5xe2x80x2. The backrest 1xe2x80x2 includes a connecting portion 11xe2x80x2 in an intermediate portion of a lower end of a rear face thereof, the connecting portion 11xe2x80x2 having fixing holes 12xe2x80x2 for connection with an arm of the L-shaped connecting plate 5xe2x80x2 that has fixing holes 51xe2x80x2. The chassis 3xe2x80x2 is fixed to an underside of the seat 2xe2x80x2 and has a lower end for connection with the leg assembly 4xe2x80x2. Further, the chassis 3xe2x80x2 includes a connecting portion 31xe2x80x2 at a rear end thereof, the connecting portion 31xe2x80x2 having fixing holes 32xe2x80x2 for connection with the other arm of the L-shaped connecting plate 5xe2x80x2 that has fixing holes 52xe2x80x2.
In use, a person sitting in the seat 2xe2x80x2 and lying his or her back on the backrest 1xe2x80x2 imparts a load to the backrest 1xe2x80x2 which is supported by the connecting plate 5xe2x80x2. The supporting point is located in a central position of the lower portion of the backrest 1xe2x80x2. Two sides of the backrest 1xe2x80x2 are subject to unequal forces if the center of gravity of the person is offset from the central vertical axis of the backrest 1xe2x80x2. Thus, the connecting plate 5xe2x80x2 could not provide reliable support to the backrest 1xe2x80x2.
An object of the present invention is to provide backrest supporting assembly that provides improved supporting stability and improved seating safety.
A chair in accordance with the present invention comprises a seat, a backrest mounted to the seat, the backrest including a rear face having two sides, a chassis fixed to an underside of the seat, a leg assembly attached to the chassis, two stays respectively attached to the sides of the rear face of the backrest, and a connecting frame. Each stay has an upper end fixed to an associated side of the rear face of the backrest. The connecting frame has two ends and an extension extending from the connecting frame. The extension is securely connected to a rear end of the chassis. Each end of the connecting frame is fixed to a lower end of an associated stay.
Two connecting plates are respectively fixed to the sides of the rear face of the backrest. Each connecting plate is securely connected to the upper end of an associated stay. A waist is securely connected between the connecting plates.
Each connecting plate includes a guide slot. The waist includes two ends each having a peg with a fixing hole, the peg being extended through the guide slot. A pressing block is attached to each peg and has a fixing hole in a first end thereof and an engaging groove in a second end thereof, the engaging groove of the pressing block being aligned with the fixing hole of the pressing block. Each peg is received in the engaging groove of an associated pressing block, with a fastener being extended through the fixing hole of the pressing block and the fixing hole of the peg.